The oldest game park in Kenya today is Nairobi National Park, which opened its doors in 1746. Surprisingly, given that it is only 7 km from Nairobi's capital city, the park still features a variety of habitats, including wide, gently sloping grass plains, riverine woods, valley thicket and bush, man-made dams and ponds, steep gorges, and dry highland forest. Only the southern boundary, which includes the Embakasi and Athi rivers and is surrounded by urban buildings, industries, roads, and airports, is available for animal dispersal. The Kitengela and Athi-Kapiti plains, which border the park on its southern border, and the park itself together make up a single natural unit.
Almost 520 different bird species can be found on the checklist of the Nairobi National Park's varied avifauna. The region has been home to one of the eight Kenya Mountains Endemic Bird Area species, 27 species of the 94 Somali-Masai biome, and 25 species of the 67 African Highlands biome. More than 5,000 Lesser Falcons have been observed roosting at the location at one time, and the park's substantial tract of undisturbed grassland is crucial for species like the restricted-range Jackson's Widowbird, which usually breeds here following good rains. Lesser Kestrel, Jackson's Widowbird, Red-throated Tit, Madagascar Pond-Heron, Corncrake, near-threatened Shoebill Stork, and Basra Reed Warbler have all been observed.. Regionally threatened species include Struthio camelus, Hieraaetus ayresii, Stephanoaetus coronatus, Ephippiorhynchus senegalensis, Polemaetus bellicosus, Anhinga rufa, Casmerodius albus, Podica senegalensis, and Buphagus africanus.
Other wildlife at Nairobi National Park, include healthy populations of large mammals among which include Zebras, Wildebeests, Elands which are July–August migrants into the park and African Lions, Cape Buffaloes, Leopards, Nile Crocodiles, Cheetahs, Hippopotamus and some more who are residents.
The park is a rhino sanctuary and numbers of the Black Rhino are steadily increasing.